newedit/editutil: In BasicHandler, only insert the character when the key is a character.

newedit/editutil/basic_mode.go

@@ -1,6 +1,7 @@
 package editutil
 
 import (
+	"unicode"
 	"unicode/utf8"
 
 	"github.com/elves/elvish/edit/tty"
@@ -57,7 +58,7 @@ func BasicHandler(e tty.Event, st *types.State) types.HandlerAction {
 		_, skip := utf8.DecodeRuneInString(raw.Code[raw.Dot:])
 		raw.Dot += skip
 	default:
-		if k.Mod == 0 {
+		if IsChar(k) {
 			s := string(k.Rune)
 			raw.Code = raw.Code[:raw.Dot] + s + raw.Code[raw.Dot:]
 			raw.Dot += len(s)
@@ -67,3 +68,8 @@ func BasicHandler(e tty.Event, st *types.State) types.HandlerAction {
 	}
 	return types.NoAction
 }
+
+// IsChar returns whether the given key is not a character insertion.
+func IsChar(k ui.Key) bool {
+	return k.Mod == 0 && k.Rune > 0 && unicode.IsGraphic(k.Rune)
+}

newedit/editutil/basic_mode_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/elves/elvish/edit/tty"
 	"github.com/elves/elvish/edit/ui"
 	"github.com/elves/elvish/newedit/types"
+	"github.com/elves/elvish/tt"
 )
 
 var basicHandlerKeyEventsTests = []struct {
@@ -85,3 +86,12 @@ func TestBasicHandler_IgnoresOtherEvents(t *testing.T) {
 		})
 	}
 }
+
+func TestIsChar(t *testing.T) {
+	tt.Test(t, tt.Fn("IsChar", IsChar), tt.Table{
+		Args(ui.K(ui.Up)).Rets(false),
+		Args(ui.K('A', ui.Ctrl)).Rets(false),
+		Args(ui.K('a')).Rets(true),
+		Args(ui.K('好')).Rets(true),
+	})
+}